640 PROF, W. BOYD DAWKINS ON [ Nov. 1902, 
sketch-map, published in 1894 in the Transactions of the Geological 
Society of Manchester,’ it will be noted that there are several 
differences, due mainly to my not having recognized the overthrust- 
faults at that time. The present map is the result of further 
examination. 
If it be compared with that published by the Geological Survey, 
it will be found that there are important differences which need 
explanation. The area in my map is considerably smaller than 
that of Mr. Lamplugh’s, and the direction and position of the 
south-western boundary-fault are different. With regard to the 
area inland, I have already pointed out that the southern boundary 
is concealed by Drift of considerable thickness, and that therefore 
it cannot be accurately ascertained without further evidence. 
In my map it is taken to be defined by the two faults and the 
exposures inland. In Mr. Lamplugh’s it is enlarged by the 
assumption that the two outliers near Glenfaba belong to the main 
mass of the Sandstone, thrown down to the east by a fault 
running north 18° east from Glenfaba Bridge, through the Drift- 
covered area to the middle of Peel Bay. There is no evidence of 
this fault on the ground, excepting at Glenfaba Bridge, and that 
is too small an exposure to give its true direction. It will not 
explain the presence of the Red Sandstone on the west side of the 
fault, nor will it explain the presence of slate north-east of 
Glenfaba Bridge, or close to the millwheel. For these reasons I 
am unable to accept Mr. Lamplugh’s map of these rocks. 
VIII. Toerr Perwian AGE, 
Nor can I accept Mr. Lamplugh’s identification of the rocks with 
the Basement Carboniferous of the south of the island, at Langness 
and elsewhere. The sandy conglomerates resting on the slate of 
the massif, and dipping under the Carboniferous Limestone in that 
district, are composed of pebbles of sandstone and vein-quartz, and 
angular masses of slate stained red. They are derived, without 
exception, from the sandstones, slates, and phyllites of the Ordo- 
viclan massif upon which they rest, and against which they abut. 
There are no chalcedonies, no hematites, no cherts, no limestone- 
pebbles, and the calcareous magnesian element is conspicuous by its 
absence. The red rocks of the north of the island are composed of 
materials derived from the waste of cliffs of Carboniferous Limestone. 
Yoredale Rocks, and of Keisley Limestone, without any trace of the 
Ordovician massif now visible at the surface. They have been torn 
away from a shore-line composed of Lower Carboniferous rocks and 
of limestones of Ordovician age. In the following table I have 
compiled a list of the materials which occur in the Brockrams of 
the Peel Sandstone and the Stack Series. 
‘ «Geology of the Isle of Man’ Trans. Manch. Geol. Soc. vol. xxii, facg. p. 592. 
